Tropical Storm COSME (Text)

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TROPICAL STORM COSME DISCUSSION NUMBER 8
NWS NATIONAL HURRICANE CENTER MIAMI FL EP032013
200 AM PDT TUE JUN 25 2013
MICROWAVE AND INFRARED SATELLITE IMAGERY INDICATE THAT THE INTERNAL
AND OVERALL CONVECTIVE CLOUD STRUCTURES HAVE CHANGED LITTLE SINCE
THE PREVIOUS ADVISORY. IN FACT...UW-CIMSS ADT ESTIMATES HAVE
LEVELED OFF AT ABOUT T3.6/57 KT FOR MORE THAN 12 HOURS. THE CLOUD
PATTERN HAS RECENTLY BECOME ELONGATED NORTH-TO-SOUTH AND THE CENTER
IS LOCATED NEAR THE WESTERN EDGE OF THE CONVECTIVE CLOUD MASS. A
BLEND OF DVORAK T-NUMBERS FROM TAFB AND SAB...RECENT ADT VALUES...
AND CIRA AND CIMSS AMSU INTENSITY ESTIMATES OF 47 KT AND 49 KT...
RESPECTIVELY...YIELDS AN AVERAGE INTENSITY OF 55 KT...WHICH WAS
USED FOR THIS ADVISORY. THE UPPER-LEVEL OUTFLOW PATTERN REMAINS
SYMMETRICAL AND CONTINUES TO IMPROVE.
MICROWAVE IMAGERY AND CONTINUITY WITH THE PREVIOUS FORECAST TRACK
WERE USED TO DETERMINE THE LOCATION OF COSME...WHICH YIELDS AN
INITIAL MOTION ESTIMATE OF 290/14 KT. THERE IS NO SIGNIFICANT
CHANGE TO THE PREVIOUS FORECAST TRACK OR REASONING. COSME IS
EXPECTED TO MOVE WEST-NORTHWESTWARD FOR THE NEXT 72 HOURS ALONG THE
SOUTHWESTERN PERIPHERY OF A STRONG AND WESTWARD-EXPANDING MID-LEVEL
SUBTROPICAL RIDGE CURRENTLY LOCATED OVER NORTHERN MEXICO AND THE
SOUTHWESTERN UNITED STATES. AFTER THAT...A RAPIDLY WEAKENING COSME
SHOULD BE STEERED GENERALLY WESTWARD BY THE LOW-LEVEL TRADE WIND
FLOW. THE OFFICIAL FORECAST TRACK IS SIMILAR TO THE PREVIOUS
ADVISORY AND IS SITUATED ALONG THE SOUTHERN EDGE OF THE TRACK
GUIDANCE SUITE...AND FOLLOWS THE SPEED OF THE CONSENSUS MODEL TVCA.
UW-CIMSS SHEAR ANALYSES OVER THE PAST 12 HOURS INDICATE THAT COSME
HAS AGAIN MOVED INTO A MODERATELY UNFAVORABLE MID-LEVEL SHEAR
ENVIRONMENT...WHICH MAY BE THE CAUSE OF THE RECENT DISHEVELED
LOOKING INNER-CORE CONVECTIVE CLOUD PATTERN. HOWEVER...THE CYCLONE
IS EXPECTED TO MOVE INTO MORE FAVORABLE MID- AND UPPER-LEVEL FLOW
REGIMES LATER TODAY...ALLOWING COSME TO STRENGTHEN INTO A HURRICANE
BEFORE THE SYSTEM REACHES SUB-25C SSTS IN ABOUT 36 HOURS. STEADY TO
RAPID WEAKENING IS THEN FORECAST TO BEGIN AFTER THE CYCLONE MOVES
OVER MUCH COOLER WATERS BY 48 HOURS...AND COSME IS EXPECTED TO
BECOME A NON-CONVECTIVE REMNANT LOW BETWEEN 72 AND 96 HOURS. THE
NHC INTENSITY FORECAST IS SIMILAR TO THE PREVIOUS INTENSITY
FORECAST...AND REMAINS CLOSE TO A BLEND OF THE DECAY-SHIPS AND LGEM
INTENSITY MODELS.
THE EXTENSIVE 12-FT SEAS RADII IN THE EASTERN SEMICIRCLE PROVIDED BY
THE TAFB IS THE RESULT OF LONG-FETCH SOUTHERLY CROSS-EQUATORIAL
FLOW GENERATING LARGE SWELLS...WHICH WILL IN TURN AFFECT MUCH OF
THE PACIFIC COAST OF MEXICO AND THE BAJA PENINSULA DURING THE NEXT
COUPLE OF DAYS AS THE LARGE SWELLS PROPAGATE NORTHWARD.
FORECAST POSITIONS AND MAX WINDS
INIT 25/0900Z 16.5N 109.5W 55 KT 65 MPH
12H 25/1800Z 17.2N 111.5W 65 KT 75 MPH
24H 26/0600Z 17.9N 113.9W 75 KT 85 MPH
36H 26/1800Z 18.5N 116.1W 60 KT 70 MPH
48H 27/0600Z 19.3N 118.7W 50 KT 60 MPH
72H 28/0600Z 20.4N 124.1W 35 KT 40 MPH
96H 29/0600Z 20.9N 129.4W 25 KT 30 MPH...POST-TROP/REMNT LOW
120H 30/0600Z 20.9N 134.3W 25 KT 30 MPH...POST-TROP/REMNT LOW
$$
FORECASTER STEWART
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